The following are incapable of succeeding:
(1) The priest who heard the confession of the testator during his last illness, or the minister of the gospel who extended spiritual aid to him during the same period;
(2) The relatives of such priest or minister of the gospel within the fourth degree, the church, order, chapter, community, organization, or institution to which such priest or minister may belong;
(3) A guardian with respect to testamentary dispositions given by a ward in his favor before the final accounts of the guardianship have been approved, even if the testator should die after the approval thereof; nevertheless, any provision made by the ward in favor of the guardian when the latter is his ascendant, descendant, brother, sister, or spouse, shall be valid;
(4) Any attesting witness to the execution of a will, the spouse, parents, or children, or any one claiming under such witness, spouse, parents, or children;
(5) Any physician, surgeon, nurse, health officer or druggist who took care of the testator during his last illness;
(6) Individuals, associations and corporations not permitted by law to inherit. (745, 752, 753, 754a)